Download Threats to Biodiversity

Threats to Biodiversity
Resource consumption and human
activities that support it form the
foundational or root threat to
biodiversity
• Current Major Threats to Biodiversity
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Habitat Related (Loss, Degradation, Fragmentation)
Pollution (Chemical, Light, and Noise)
Overexploitation
Invasive Species
Anthropogenic Climate Change
Disease (lesser threat to most taxa)
UV radiation (primarily threat to amphibians
• Synergistic Effects of Threats
Habitat Loss, Degradation, and
Fragmentation
Overexploitation
Bioaccumulation
Synergistic Effects (1 + 1 = 3+ ?)
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Coral reefs
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Climate change
Acidity
Fungi
Pollution
Cascade Effects One factor can create a trophic cascading domino-like effect
within an ecosystem that leads to secondary losses of other species
The fungus that causes
sudden oak death
Secondary Species Loss and Extinctions
Top-Down Regulation by Carnivores
Ecological Release
• What are the primary threats to
biodiversity?
• How can these threats have effects
greater than their individual contributions?
– Provide an example
– What is a trophic cascade, provide an
example, and describe how the secondary
loss of species occurs?
In thinking about Extinction let’s recall the following
info…
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Habitat Generalists – can exploit a variety of habitats within an
area/range; can easily switch from available and/or preferred to less
preferred habitats
Examples: White-tailed deer, elk, raccoon, bluegill, white oak
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Habitat Specialists – can exploit (usually very well) 1 or only a few
habitats within an area/range; most habitats unsuitable and cannot
be used
Examples: Kirtland’s warbler, running buffalo clover, desert pupfish,
red-cockaded woodpecker
What types of Species are Most Vulnerable
To Extinction?
Rare Species – population densities, range, and habitat
specificity
- Species with restricted geographical range
- Species with only 1 or few populations
- Species with small population sizes
• Declining Species
• Occur at Sites of High Human Exploitation (poverty,
resource extraction, hunting/harvesting, urbanization,
pollution)
Note: Understanding the characteristics of extinction-prone species is important for anticipating how vulnerable
species and biological communities are to certain activities. Even w/o detailed data we can make generalizations that
help predict impacts and potential loss of these species and communities, but also helps to use and apply our valuable
conservation and management dollars and efforts wisely.
Other Predictors of Extinction Vulnerability
(Conceptualize why for each case)
• Large Space (Home Range) Requirements (wolverine, grizzly
bear, tiger)
• Large-bodied Animals (bison, elephants, rhinos)
• Ineffective Dispersers (plants with heavy, unpalatable seed pods,
those that are heavily predated
• Seasonal Migrants (pronghorn, neotropical migrant songbirds)
• Species w/ Little Genetic Variability (cheetah)
• Species w/ Specialized Niche Requirements (desert pup fish,
Kirtland’s warbler)
• Species found in relatively stable environments (tropical
only species, pristine lakes)
• Species that form permanent or temporary aggregations
(schooling fish, herding animals)
• “Naïve” species w/ no prior contact w/ humans (dodo bird)
• Species closely related to other extinct or near
extinct/threatened species (rhinos, oryx, whales)
What factors are most threatening to biodiversity?
Note that while habitat loss and degradation remain the primary threat to most taxa, some organisms also
face high threats from other factors.
Where are most taxa threatened with extinction?
Note: Black bars indicate # of threatened
species
Why are some places in the U.S. such hot spots of endemism? What is it about these geographic
areas that make communities and the species they harbor relatively more vulnerable to extinction?
Conservation Databases
IUCN (International Union for the Conservation of Nature
and Natural Resources) Red List System:
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Created in 1963
System to classify threats to individual species
Classifies all species into 9 Status Categories
Not evaluated, Data Deficient, 3 Threatened Categories (Vulnerable, Endangered,
Critically Endangered), 2 Extinct Categories (Extinct in the Wild, Extinct), Near
Threatened, and Least Concerned (see next slide for how the classification
decision tree is constructed)
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General Evaluation Criteria by which Classification Decisions are Made:
– 1) population size and trends
– 2) geographic range
– 3) quantitative predictive models
IUCN Decision Tree
Note: By tracking the conservation status of species over time we can evaluate whether conservation
measures are working.
If a species is considered threatened according to general criteria…then the
“Red List Criteria” (Table 8.2 below) are used to further classify it into one of
the 3 threatened categories.
“Blue List”
• http://www.bluelists.ethz.ch/
• Organized by few Swiss academics
• Lists IUCN threatened (Red List) species that are
responding to conservation measures and suggests
further measures to continue success.
Natureservee
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http://www.natureserve.org/
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Covers U.S. and some of Canada and most of Latin America
Backed by The Nature Conservancy (non-profit)
Gives a conservation status ranks to “elements of interest” meaning
that in addition to individual species, also gives a conservation
ranking to biological communities
Ranking Criteria include:
– # of remaining pops.
– # of estimate individuals remaining (or extent/size of remnants
for communities)
– # of protected sites that harbor the element
– degree of threat
– general vulnerability to known threats
Ranks run from 1 thru 5, with 1 being critically imperiled to 5 being
demonstrably secure
Excellent biodiversity pubs at:
http://www.natureserve.org/publications/library.jsp
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Dealing with Biodiversity Threats: A
schematic way to tackle them
Knowledge of Threat (where, how, extent, why)
Identify priority
actions
Develop strategies
Implement plan to
slow, mediate, or
reverse threat